From an article written by the University of Montreal and published in the phys.org web site:
“In Quebec, gravestones did not come into common use until the second half of the 19th century, so historical cemeteries contain many unmarked graves. Inspired by colleagues at Barcelona’s Pompeu Fabra University, a team of researchers in genetics, archaeology and demography from three Quebec universities (Université de Montréal, Université du Québec à Chicoutimi and Université du Québec à Trois-Rivières) conducted a study in which they combined genealogical information from BALSAC (a Quebec database that is the only one of its kind in the world) with genetic information from more than 960 modern Quebecers in order to access the genetic profile of Quebec’s historical population. The results, published in the American Journal of Physical Anthropology, suggest the capabilities that this method may offer in the near future.”
“The first author of this study is Tommy Harding, a postdoctoral researcher at Université de Montréal who specializes in DNA sequencing. BALSAC, he said, ‘is a fabulous database for researchers, because both the quantity and the quality of the data that it contains are truly exceptional. The parish records meticulously kept by Catholic priests have been very well preserved so that today, thanks to advances in technology, it is possible to use this data to identify the bones from unmarked graves.'”
You can read a lot of details about how this was accomplished in the article at: https://phys.org/news/2020-02-anonymous-combining-genetics-genealogy-dead.html.